AT&T ISDN 7507 Telephone

[Babybearjs]

this phone is on Ebay and it looks like its an older style ISP phone. Can this phone be used on C*net? does it require the web to get a dial tone?

[Fabius]

ISDN: Integrated Service for Digital Network. An early set of communication standards for simultaneous digital network transmission. I remember GTE putting in ISDN lines to the big Bethlehem Steel plant in Northwest Indiana. This was in the early 1990s. The ISDN lines didn't last in service very long.as they were replaced in a few years with newer technology. I don't think any ISDN is still in service?

https://en.wikipedia.org/wiki/Integrated_Services_Digital_Network

[Babybearjs]

good thing I asked.... the phone is on ebay starting at 9.99. sounds like a worthless phone to purchase . I thought I'd ask about it, because it looked like it connected to a LAN jack and could be used as a VOIP phone.

[twocvbloke]

I remember accessing the web via ISDN, a whopping 128Kbps, at the time the fastest speed you could get...

I think over here at least there's still some legacy ISDN in places, but long since dropped from support (so if it fails, it's upgrade or forget it, with  total cut-off date of 2025), BT attempted to rebrand it too with the ever increasing broadband, they called Dialup "Narrowband", ISDN "Midband" and of course ADSL was "Broadband", never caught on though...

[unbeldi]

This is not at all a VoIP telephone.  Really has nothing to do with IP.

I believe these are used with a Definity PBX system, which I think went to Avaya after the sell-off.  ISDN is the digital successor to analog telephony, and is still in wide use around the world.

Both Primary Rate (PRI) and Basic Rate (BRI) Interface service used 8-pin modular connectors, PRI delivers 23 (+1 control) channels, while BRI delivers only two 64kbit/s channel (plus 1 16kbit/s data channel).  This is what this telephone uses.   BRI was never successful in the US to deliver voice to the home, but it is the standard still these days in many countries around the world.  In the US only the PRI service is used for business voice and is still ubiquitous, but certainly gradually loosing against VoIP.

I don't know whether this particular set can be used with any BRI ISDN service, some or many of the AT&T terminals require feature cards that have activation codes in them, I believe, but I welcome any corrections.
In principle, ISDN phones could be used with a BRI channel card for your channel bank. Most channel bank makers such as Carrier Access for the ADIT channel banks, had or have plugin card.

[Doug Rose]

ISDN is still around. used for older video applications. Mostly for Business'  that have not upgraded to IP service. ISDN is a PITA, a 128K circuit that you would have to bond to make a passable 384K video. ISDN phones came and went very fast. 128K is 128K....slow....Doug

[Fabius]

ISDN is a PITA, a 128K circuit that you would have to bond to make a passable 384K video. ISDN phones came and went very fast. 128K is 128K....slow....Doug

That's what they did at Bethlehem Steel. With 384k the video was still not really great. GTE replaced it with DS-1 (T-1) based system at 1.544mbps.

[Babybearjs]

so, they used dedicated equipment? in order for the phone to work, it had to be connected through a ISDN service card? Interesting....

[unbeldi]

so, they used dedicated equipment? in order for the phone to work, it had to be connected through a ISDN service card? Interesting....

ISDN provides voice, video, data, as well as signaling, digitally on the same wire at the same time with guaranteed error-free delivery. The 'wire' has a bus architecture, you chain multiple (up to eight) terminals, but only two can be active at any given time.

[Dan F]

ISDN is widely used in the radio broadcast industry. Although they are fewer stations using it because ip network audio is much less expensive. I have a home studio and an ISDN line installed I use for high quality audio transmission.

ISDN: Integrated Service for Digital Network. An early set of communication standards for simultaneous digital network transmission. I remember GTE putting in ISDN lines to the big Bethlehem Steel plant in Northwest Indiana. This was in the early 1990s. The ISDN lines didn't last in service very long.as they were replaced in a few years with newer technology. I don't think any ISDN is still in service?

https://en.wikipedia.org/wiki/Integrated_Services_Digital_Network

[CanadianGuy]

I vaguely remember Howard Stern talking about using ISDN in his radio days. I think he described how they'd go on remote locations and the station would order an ISDN line installed for that event. I could be mistaken, though.

I might be imagining this, but didn't stations also get the phone company to run a temporary drop when they were on a remote? Ah the days before cell phones!

[unbeldi]

I might be imagining this, but didn't stations also get the phone company to run a temporary drop when they were on a remote? Ah the days before cell phones! Yes, it was very common for voice transmissions from stadiums such as sporting events, etc. to use a dry point-to-point private line that would  be used with a 331 portable telephone set, such as the one pictured on the right. For higher quality, and stereophonic audio, an ISDN line was needed.